8 
SIR J. B. LAWES AND PROFESSOR J. H. GILBERT ON THE 
been removed in the crops during the five years to 1882 inclusive, from the Vida 
sativa plots 366 lbs. had been removed during the same period. Further, whilst 
from the Trifolium ro'pens plot there was no nitrogen removed in 1883, the year of 
soil sampling, from the Vida plots 101 lbs. were removed in the crop just before the 
soil sampling. It is seen that, under these circumstances, there remained, per acre, in 
one of the Vida plots 81'5 lbs., and in the other 91 lbs., less nitrogen as nitric acid 
to the depth examined than in the Trifolium re'pens soil. 
If we confine attention only to the amount of nitrogen removed in the Vida crops 
in the year of the soil sampling, and assume that there had been only as much at the 
disposal of the plant as in the case of the Trifolium plot, it is obvious that the 
deficiency in the Vida soils very nearly corresponds with the amount removed in the 
crop, which was about 100 lbs. Indeed, it may safely be concluded that most, if not 
the whole, of the nitrogen of the Vida crops had been taken up as nitric acid. 
But there had probably been more loss by drainage from the Tdfolium plot without 
growth than from the Vida plots with growth, and with, at the same time, much 
more upward passage and evaporation. 
It must also be borne in mind, that the Vida plots had, during the preceding 5 
years, 1878 to 1882, yielded an average of more than 70 lbs. of nitrogen per acre, and 
in the immediately preceding year (1882), 146 lbs. Further, the* amounts taken up 
by the plants each year must have been much greater than the amounts removed in 
the crops; for there must have been annually a large crop-residue, which would yield 
nitric acid for succeeding crops. Much of these large amounts of nitrogen must 
obviously have had some other source than the original surface soil, since it gained 
rather than lost under the treatment. If this source were not the atmosphere, but 
the subsoil, it must have been taken up, either as nitric acid, as some other product 
of the change of the organic nitrogen of the subsoil, or as organic nitrogen itself 
Further, as the Vida crops were large in the previous year, 1882, so also would their 
nitrogenous crop-residue be large, and contribute correspondingly large amounts of 
nitric acid for the crops of 1883. But the crops of 1883 were also large, and they, in 
their turn, would leave correspondingly large nitrogenous crop-residues; leaving a 
large proportion of the amount of nitrogen removed in the crops to be otherwise 
provided for than by previous residue. 
Lastly in reference to these experiments, it is seen that at each of the 12 depths, 
down to 108 inches, the Vida plots where there had been growth, contained less nitric- 
nitrogen than the Trifolium repens plot where there had been no growth. The 
difference is much the greatest in the first 18 inches, within which the Vida throws 
out by far the larger amount of root; but it is very distinct below this point, and the 
supposition is that, under the influence of the growth of the Vida, water had been 
brought up from below, and with it nitric acid. In fact, compared wdth the Trifolium 
repens plot, the mean for the two Vida plots showed less water in the soil dowm to 
